This project is directed to study the interrelationships between the disturbances of systemic and intrarenal hemodynamics and the alterations of kidney function and sodium excretion which occur in cardiovascular diseases such as hypertension and congestive heart failure. The present application proposed to investigate the alterations of renal perfusion (radioactive microsphere technique) and hormone overflow (renal blood flow x arterial-renal vein hormone concentration difference) which occur in dogs during chronic changes in systemic hemodynamics induced by alterations in sodium balance or by acute reduction of cardiac output by partial occlusion of the thoracic vena cava in dogs. Additional experiments are designed to investigate the extent to which the renal nerves, the renin-angiotensin system and the renal prostaglandins modulate renal blood flow and urinary electrolyte excretion in such experimental models of edema formation and also in patients with hypertension and/or oliguric renal failure.